Understanding summer wind systems over the eastern Mediterranean in a high-resolution climate simulation

Regional and local wind systems are often complex, particularly near coastal areas with a highly variable orography. Thus, the realistic representation of regional wind systems in weather and climate models is of strong relevance. Here, we evaluate the ability of a 13-year convection-permitting climate simulation in reproducing the interaction of several regional summer wind systems over the complex orography in the eastern Mediterranean region. The COSMO-CLM simulations are driven by hourly ERA-5 reanalysis and have a spatial resolution of 2.8 and 7.0 km. The simulated near-surface wind fields are compared with unique very high-resolution wind observations collected within the Dead Sea Research Venue project (DESERVE) and data from the Israel Meteorological Service synop network. The high-resolution COSMO-CLM simulations largely reproduce the main characteristics of the regional wind systems (Mediterranean and Dead Sea breeze, slope winds in the Judean Mountains and winds along the Jordan Rift valley), whereas ERA-5 is only able to represent the Mediterranean Sea breeze. The high-resolution simulations substantially improve the representation of regional winds, particularly over complex orography. Indeed, the 2.8 km simulation outperforms the 7.0 km run, on 88%$$ 88\% $$ of the days. Two mid-July 2015 case studies show that only the 2.8$$ 2.8 $$ simulation can realistically simulate the penetration of the Mediterranean Sea Breeze into the Jordan Rift valley and complex interactions with other wind systems like the Dead Sea breeze. Our results may have profound implications for regional weather and climate prediction since very high-resolution information seems to be necessary to reproduce the main summertime climatic features in this region. We envisage that such simulations may also be required at other regions with complex orography.

Automated summary

This study evaluates the ability of a 13-year climate simulation to reproduce the interaction of regional summer wind systems in the complex orography of the eastern Mediterranean region. The high-resolution simulation substantially improves the representation of regional winds, particularly over complex orography. The results have important implications for regional weather and climate prediction.